Method of making printing-plates.



'M. A. DROIATCOUR. METHOD OF MAKING PRINTING PLATES. IOATION FILED JAN. 2, 1909.

ABPL

Patented Mar.15,1910.

w V I o 3 3 P m 5 I Q I! a 4 a. a I P a I u. .v v i I I I m P m mm m MICHAEL A. DROITCOUR,

OF CHICAGO, ILLINOIS, ASSIGNQB 'IQ MIEHLE' PRINTING;

PRESS AND MANUFACTURING COMPANY, OF CHICAGO, ILLINOIS.

METHOD OF MAKING PRINTENG-PLgTES.

seas-re;

Specification of Letters Patent. Pa$ gm tjgd Ma r, 15;, 191(3),

application filed January 2, 1308. Serial Ito. MOAEB.

and less pressure on those portions of the printing surface which produce the high lights of the impression, and it is customary among printersbecause of this, to increase the height of the the form by placing one of paper or underlay under such portions, or to build up or overlay the portions of the impression cylinder coming in contact with such solid portions of the form.

By my invention I so treat the matrices, from which the printing plates are formed, that in the process of making the plates from plastic material, such as celluloid they will be given increased thickness where necessary to produce the desired solids and be thinned where high. lights" are desired, and the printer can use well plates without placing any underlay 7 under the form or overlay on the cylinder.

My invention consists in the novel process of making such printing plates from plastic material, and is described asfollows:

To facilitate ready coinprehension of the process I will refer to the accompanying diagrammatic drawings in which:

Figure 1 is an enlarged view of part of a matrix. Fig. 2 is a view of such matrix with underlays applied thereto, also showing a plate pressed thereon. Fig. 3 is a view of solid portions of or more thlcknesses such plate removed from the mold in Fig. 2

and supported on theunderlay. Fig. 4 is a sectional view of a finished plate.

7 In making the matrix several sheets or layers of matrix paper, are pasted together with any of the well known pastes used by stcreotypcrs, but I preferably use the paste described in my application Serial Number 488,804 tiled April 9, 1909, and when the matrix blank is properly seasoned and ready for use, it is laid upon the form from which the matrix is tobc made, and pressed against the same by flat or platen pressnrepreferof the plate are removed, as

ably applied simultaneously to all parts of the blank by suitable means, and then set the matrix under heat and pressure while in contact with the form. The matrix M thus formed will have the same thickness throughout, from back to the inner face of the intaglio type-matrices therein, as indicated by the dotted linem'in Fig. 1, if care has been taken to have the form in proper condition at the time the impression is taken on the matrix. In some cases, I prefer to give the matrix a metallic face in order to preserve the fine lines, or screen in half-tone work, and this I do by facing the matrix blank with a sheet of tin-foil, and then pressing them into the form and set them with heat. Before making a printing plate from such matrix, I place under the rear face of the high light portions of the matrix one or more layers or underlays U of paper, which of course thicken such portions ofthe matrix, in accordance with the tone desired for the subject, so that printing plate I made from such matrix will have portions 2) corresponding to the raised portions u of the matrix, the portions p forming slight depressions in the printing surface of the plate;- and parts p form corresponding protuberances p on the back of the plate before it is finished. These projections onthe back hereinafter described, to reduce the back of plate to a uniform plane surface, consequently the finished plate will be thinner at the points 1), the high lights, see Fig. 4:. I thus lessen the pressure whichwill be exerted upon the thin portions of the plate by the cylinder or platen when printing therefrom. The thickening of the matrix by the underlays U is of course graduated to suit the nature of the subject to be printed.

From the above describedmatrix having the underlaid high-light portions, I proceed to make printing plates of'pla'stiomaterial as follows: A. sheet of celluloidr'or other plastic material P capable of being softened so it can be molded upon the matrix and afterward hardened, is suitably softened and then laid directly on the face of the matrix, and is put under pressure so that the softened celluloid or other plastic material is forced to conform to the depressions of the matrix, see Fig. 2. The consequence is that the printing surface of the material or plate P is formed exactly the loo " jected to any pressure which can injure it, or distort the material in it, or stretch it,

. part thereof or a filler which adheres there,-'

' when thus shaved or I plate was molded upon thereon at printing face trix,

desired. The finished eeaaia Having thus described my invention what claim as new and desire to secure by Letters Patent thereon is: f

- 1. The improved process of making printing plates from plastic material, consisting in forming a matrix; then applying suitable nnderlays to the back-ofthe matrix; then applying a blank of suitable material in a p astic' condition to the face of themat-rix; then pressing the blank a ainst the matrix to'form' a plate having. depressions in its printing surface corresponding to the overlays on the back ,of the matrix, and protuberances on its back corresponding to the depressions in its face;-tl1en supporting the printing face of the plate at the depressions and removing the projections on the back of the plate. e I

I 2. The herein described process of making printing plates from plastic material; consisting in first forming a.- suitable matrix,

.second applying underlays to "the back of the matrix; third placing a-blank of plastic material on the applying. pressure thereto, thereby forming depressions on thesurface of the resultant plate corresponding back of the matrix, and protuberances on the back of the plate corresponding with the depressions in its face; then shaving or grinding the back such protuberances and reduce the back of the plate to a plane surface without changing the printing face thereof.

3. 1h process of making printe improved m lates from lastic material COHSIStIII b a a verse face of the plate has protuberances 30 points correspondingto the un-. derlays U in the matrix, see Fig. 2; After the plate P is thus formed, it shave or grind t e rear-or under surface of it to remove l the protuberances, either while its printing 1 face is still in contactwith and sup orte i by the matrix see Fig. 2, or supporte' y the underlays U, see Fig. 3, so such rear surface will be made plane and smooth. .As a result of this shaving the plate will be of irregular thickness between its rear face and its exactly in accordance with and in proportion to the thicknesses of the original underlays; and such plate will be thicker on solids and thinner on high lights, therefore while the back of the plate is plane-surfaced its printing surface is uneven. While the plate is being shaved or ground its printing face must be supported at all the thin points by the matrix or the underlay so that the plate cannot spring or yield under the knives or cutters and so that its printing surface is not sub reverse of the matrix face; while the ire-1 or leave any weak pockets in it, which would alfect its register-in color printing." The back of the plate P is usually an integral The plate is finished and ready for use ground. By thus shavmg the plate while its printing face is supported as described, I do not add to the raised part of the printing face, but the thickness of the plate at the high light por- 1n forming a suitable matrix; then apply tions is reduced slightly. more than that at --ing suitable underlays to the back of the the solid portions, as shown in Fig. 4. matrix at the desired points; then a p lying a blank of suitable material in a p astic condition tothe face of the matrix; then compressing the blank, matrix, and underlays to form a plate having depressions in Instead of shaving or finishing the plate i while it is supported by the formative mait can be removed from such matrix, and supported on its printing face, while it is being shaved, by the same underlay which was under the formative matrix when the I i it see Fig. 3. This overlays on the back of the matrix, and pro-' tuberances on its back corresponding .to the of injury to the ma-' depressions in its face; then placing the and i printing face of the plate upon the matrix underlays and shavingior grinding the back of the plate while supported on such nnderlays to remove said duce the back of the plate to. a plane surface without changing the prii'iting face thereof.

MICHAEL A. DRQI'ICOUR. Witnesses:

H. M. MUNDAY, EDWARD S. EVARTS,

obviates the possibility trix itself that might occur if the matrix plate were not in exact register at the time I of shaving-the latter; while at the same time the plate will befinished properly with its high light portions thinned to they extent plate has a perfectly plane surfaced backand an unequally sur- 5' faced printing face, the hi 'h'li ht portions being slightly lower than the other portions of the plate, see Fig. 4.

face of the matrix and to the overlays on the its printing surface corresponding to the protuberances and red 

